Telescopically extendable and retractable loading ramps, which are stowable in a cargo bed, have been heretofore used to load and unload cargo from vehicular cargo beds. In U.S. Pat. No. 4,685,857 by Goeser et al., there is disclosed an adjustable load carrying ramp designed to fit within a bed of a vehicle such as a pick-up truck. The Goeser et al. apparatus relies primarily upon a ramp assembly comprised of a base or platform frame assembly which rests upon the vehicular bed and an extendable ramp assembly slidably mounted onto the undercarriage of the platform frame. The ramp assembly is extendable in a sliding manner therefrom to a sloped or ramping surface for rolling objects from ground level onto the load-carrying platform. The Goeser et al. ramping device basically affords two operational planes. One of the operational planes is afforded by the platform frame which rests upon the cargo bed in a substantially parallel and horizontal relationship thereto and the other is a single plane of relatively steep inclination as afforded by the extended ramp assembly.
Another extendable and retractable ramp assembly for use with pick-up trucks is disclosed in U.S. Pat. No. 4,624,619 by Uher. The Uhler assembly generally comprises a main carrier or platform frame for emplacement onto the vehicular bed and a hinged, telescopically extendable and retractable ramp section carried beneath the platform frame. A lateral hinge extends across the entire width of the Uhler ramp section which allows for a portion of the extended ramp section to clear a lowered pick-up tailgate. The Uhler ramping section which extends above the lowered tailgate lies in a parallel and horizontal relationship to the vehicular bed and the platform frame. The hinged ramp section simply serves as a platform frame extension for clearing the lowered bed end gate at which juncture (i.e. at the hinge) a relatively abrupt angular ramping decline is provided for the ramping of cargo thereupon. Uhler relies upon TEFLON strips bolted onto the tailgate inner wall so as to permit the telescoping ramp section to more freely slide into and out of the platform frame undercarriage. The Uhler assembly is similar to the Goeser et al. assembly in that when the ramping device is telescopically extended for loading and unloading it also affords a single inclined ramp or grade for the loading and unloading of cargo thereupon. Except for the relatively steep ramping grades, the Goeser et al. and Uhler assembly may be used in the ramping of a high clearance vehicle but both are generally unfit for ramping of low clearance wheeled vehicles thereupon. This unfitness is generally attributable to the abrupt angular or planar grades which must be negotiated during the ramping use of these devices.
U.S. Pat. No. 4,601,632 by Agee discloses another ramping device for use with pick-up trucks. The Agee device basically comprises an elongated ramp sleeve which fits upon the cargo bed and an extendable hinged ramp access section. Similar to Uhler, the hinging thereof essentially allows the ramping access section to extend the elongated ramp sleeve beyond the lowered end tailgate whereupon the remaining portion of the ramp section forms a relatively steep ramping grade. The loading and unloading of cargo with the Agee device correspondly involves two operational planes, namely the planar ramping grade from ground level to the lateral hinge juncture and the substantially horizontal plane formed by the ramp sleeve and the corresponding tailgate access extension thereto. The Agee device is of a width sufficient to afford a single track trackage thereupon. Consequently, multiple sleeved ramping devices are required to accommodate multiple laterally tracked vehicles such as the conventional three and four wheeled vehicles.
Although extendable and retractable ramping devices for transport upon pick-up trucks and the like have been known for several decades, such devices have failed to incorporate into a single device, the prerequisitial functional, structural and design attributes as required to meet their intended use. Included amongst such prerequisitial attribute wants are: the need for a compact ramping structure which does not sacrifice or detract from the intended ramping cargo carrying capacity or safety of the device, a device which may be inexpensively manufactured, compactly shipped and readily assembled at a distinct location by its users, mechanical soundness in structure, operational use and weight bearing capacity so as to meet the diverse and demanding requirements of its intended use, improvements in mechanical ease of operational use in extending, retracting and stowing of its undercarriage, a device which substantially reduces the hazardous conditions inherently attendant to conventional portable ramping devices, a device effectively reduces over-all ramping span so as to permit its effective use within tight ramping quarters, a device which would permit low clearanced wheeled vehicles (e.g. riding lawnmowers equipped with low clearance mowing decks, motorcycles, etc.) to clear the ramping passageway with equal effectiveness as the high clearanced vehicles clear, a device of a design and capacity to stow more lengthy ramping members within its undercarriage, and a device which effectively reduces the over-all ramping grades so as to substantially reduce slippage, sliding, traction and power requirements, as well as the concomitant ramping hazards during its operational use.
Recognizing such shortcomings and functional deficiencies, the inventor sought to create and develop a compact, portable, retratable, extendable, stowable ramping device embodying these combined functional and desirable attributes heretofore wanting into a single ramping device. The advantages and versatility of the ramping device as afforded by this invention over the prior art ramping device will become more readily apparent from the accompany drawings and following written description of the invention.